There is one basic principle to remember. On any one deal, only one side or the other, not both, can preempt. If opener preempts, your jumps are no longer weak. They show specific strong hands.
Consider a a Standard American weak
But what's the difference between doubling and bidding spades vs. jumping in spades immediately? The treatment I prefer in my regular partnerships is not universal, but I have found it effective. An immediate jump in a new suit says, "This suit will be trump, and I am within one trick of making this contract. Look just at your trump honours and your side aces and ace-kings, and decide how high you want to raise me." Advancer can raise or cue-bid. If, on the other hand, you want your partner to look more at his overall strength, and not just at his aces and trumps, doubled first, then bid your suit, showing a hand that will benefit from general strength in advancer's hand, not just specific cover cards. For example, over a weak 2, I would double and then bid spades with
Discuss with your partner what a cuebid of the opponent's suit means after a 2- or 3-level opening in front of you. If 1-
A common expert alternative to my use of cuebids and jump shifts is called "Leaping Michaels," using two of the jump shifts to show specific strong two-suiters. Over a weak 2 opening, 3 would show the majors, 3 hearts and clubs, and 3 spades and clubs.Top of page Exit this page
Beware that any weak bid, however "forcing" it is in principle, may in fact be dropped unexpectedly by responder if he is weak and happens to have length in opener's suit. You can still adopt a "pass first with very strong hands" approach, but there are two hazards with this. One, the small risk of not getting a second chance; two, the considerably larger risk that the bidding will be bounced uncomfortably high by further preemption before you get to bid again. Opposite almost all weak bids not showing a specific suit, responder has some means of bouncing the bidding when he has a hand that caters to more than one of opener's hand types. For instance, after a Multicoloured 2 showing a weak two-bid in either major, a weak responder can bid 3 if he has 3-card support for both majors, letting opener pass 3 with hearts or correct to 3 with spades.
Also beware of the additional bidding space which you give opener's side with your cheapest actions. Doubling, in particular, can give the opening side a chance to escape in a cheap contract they never could have stopped in without your interference. This makes it particularly important that doubler has values in the suit he doubles artificially, in case he is called upon to defend that doubled contract.
You need to have a way to bid every suit, since opener has not promised any one suit.
This is the most common convention in this category. A Multi 2 opening can show a weak two-bid in either major. Some pairs play "mini-multi," allowing only these two hand types; others also use
As common in Eastern Europe as the Multicoloured 2 is in Britain and Western Europe, the Wilkosz
I use the same fairly simple defence against both Multi and Wilkosz:
There are many other more complicated defences to these openings (using X for 2-suiters including diamonds and 2NT for 2-suiters not including diamonds, or using 2M to show 4 of the bid suit and 5 of something else, for example.) If you like exotic science, feel free to experiment -- but if you like exotic science, you probably aren't here reading a primer on coping with other people's weird opening bids!Top of page Exit this page
Defending against an opening is much easier if opener has promised a long suit: you have a cuebid of opener's suit available to use the same way you use a takeout double of a natural preempt. In fact, for three well-known conventions that fall in this category, that's really all you need to know!
Rubin Two-Bids have the 2-way flavour of Multicoloured 2, but only one weak meaning per call: a 2 opening is either weak with diamonds, or various strong hands; a
Bergen Two-Under Preempts are slightly more complicated.
Namyats, much more widely used than Bergen or Rubin, is also a kind of Two-Under Preempt: a 4 or 4 opening to show a solid heart or spade suit, respectively. Discuss with your partner whether the cue-bid is a 3-suit takeout or is Michaels, promising the other major and just one of the minors.
More complicated defenses exist, that make it harder for the opening side to exploit the extra space you offer their side if you double or overcall cheaply, but given how rarely you will face these methods almost anywhere in the world, I doubt it is worth your trouble to develop and memorize them.Top of page Exit this page
The defence against an conventional call promising the bid suit plus another suit is essentially the same as against a natural opening. The simplest defence to an opening like Muiderberg 2 showing a weak hand with hearts and a minor is to use the same methods as you do over a standard weak two-bid in hearts.
My recommendations vs. weak twos are simple:
One popular additional convention I recommend is Lebensohl after a takeout double of a weak two. Like Lebensohl after a 1NT Opening, the principle is to clarify responder's strength better in exchange for giving up a natural invitational NT bid. If doubler's partner bids 2NT, doubler must call again -- 3C with any minimum hand or average double, anything else with such a powerhouse he is interested in game even opposite a weak partner.
Lebensohl over weak twos is only for established partnerships with good memories, but in the right hands, it gains much more than it gives away.
Calls promising only 4 cards in the bid suit are a bit harder to defend against. You can treat them the same way as weak twos too, but you will occasionally lose a good fit for your side when your side has 8 or 9 cards in opener's bid suit. You may prefer to treat a convention like the Ekrens
On the surface it sounds like there can be no such convention. But the Gambling 3NT is a common such convention. Opener promises a solid minor suit, either one -- and if responder has three suits stopped, obviously the one he doesn't have is the one his partner has, and he can safely pass out 3NT, expecting to score one or two of his stoppers plus run seven or eight tricks in partner's minor. Responder with a weak hand can also pass out 3NT, willing to go down several tricks undoubled as a sacrifice against your side's likely game, escaping to 4 of a minor if 3NT gets doubled for penalty.
The defending side needs a mechanism to be able to double 3NT for penalty, to stop opener's side from stealing the hand cheaply in this way. There are two ways to do this: use double to show both majors, expecting partner to pass if he has the minors stopped, or use double as penalty, allowing partner to pull the double if he has a 6-card major and would rather try for game.
For simplicity's sake I recommend treating a Gambling 3NT opening the same way you treat a natural 4 or 4 preemptive opening.
The Kantar 3NT works about the same way as the Gambling 3NT, but opener's solid suit is always a major. It is much rarer for responder to pass 3NT instead of playing 4 of a major, but still possible. Opener's side is more likely to become declarer, though, because they can bid 4 or 4 over your 4 or 4 overcall, instead of having to sell out or compete to the 5-level. Again, I suggest suit bids are natural, and double can be either takeout or penalty, matching whatever you do over 4-level openings.
Finally there is one other weak bid not promising a suit, which you are unlikely to ever meet: the "fert" 1-level opening. There are bidding systems in which Pass promises 8 or more points, and all 0-7HCP hands must make some other bid (most commonly 1.) These so-called "forcing pass systems" are disallowed in almost all countries except in long team matches where you have time to study your opponents' system notes and prepare a detailed defence.
If you are playing in a world championship, you will of course do your homework and prepare a thorough defence to this type of system; but if you meet such a pair practicing at an online bridge site and choose to play against them, an adaptation of the Wilkosz/Multi defence (double = semibalanced 11-14 with opener's suit or any 19+, 1NT = 15-18, new suits natural, jumps strong) is better than being caught completely unprepared.